Heading Indicator | Wander Flashcards
Even on the ground, the DGI will change its heading at ___ degrees per hour
15
Real wander is AKA ___ wander
mechanical
Real wander comes from ___ in the bearings, power fluctuations, and other ___
friction imperfections
Real wander is ___ and can be measured only be checking the heading
unpredicatble
Real wander is sometimes called ___ wander
random
A ___ gyro has no random wander
perfect
Apparent wander is where the spin axis remains aligned to a point ___ ____ as the plane of reference changes, making the gyro appear to precess
in space
Earth rate is _ to _
N S
Earth rate is __ degrees per hour at the poles
15
Earth rate is ___ at the Equator
0
Earth rate varies with the ___ of latitude
sin
Earth rate is ___ in the N Hemisphere, ___ in the S Hemisphere
Right Left
The sign is ___ in the N Hemisphere
-
Apparent drift is corrected for with a ___
latitude nut
Transport wander is the phenomena where the spin axis appears to move because you are crossing ___ and ___ becomes a factor
meridians and convergency
Flight to the West will cause ___reading in the Northern Hemisphere
over
Flight to the East will cause ___reading in the Northern Hemisphere
under
Eastward flight ___ the apparent drift because the gyro is rotating faster than the speed of the Earth
increases
Latitude nut introduces an equal and opposite precession force to counteract ___ drift
apparent
Latitude nut introduces ___ wander to correct for fine drift
real
When wound outwards, the latitude nut exerts a ___ force against the balance weight on the other side of the inner gimbal, where it is mounted.
greater
Without any other influence, going North of the preset latitude causes the DGI to ___read, South to ___read
under over
Total Gyro Drift =
Earth Rate + Transport Wander + Latitude Nut + Random or Real Wander
Earth Rate =
15 x Sin( Latitude per Hour )
